Magnetic disk drives often include a magnetic head for perpendicular magnetic recording in order to provide for high recording density, large capacity, and miniaturization. In such a magnetic head, a recording head includes a main magnetic pole which generates a perpendicular magnetic field, a write shield which faces the main magnetic pole with a write gap therebetween, and a coil that causes a magnetic flux to flow through the main magnetic pole. In addition, a magnetic recording head for high-frequency assisted recording has been proposed, in which a high-frequency oscillator is disposed between a main magnetic pole and a write shield (i.e., within a write gap).
However, in the manufacture of a recording head and recording medium, it is difficult to produce a recording head for high-frequency assisted recording under optimal conditions. This is due in part to variations in a magnetic pole shape and a resonance property of the recording medium.